ATV Jord og Grundvand

1. ATV Jordog Grundvand Naturligtforekommendestofferijordellergrundvandogderessundhedseffekter

2. Project presentation • Geo-Center project, financed by GEUS and AU (2011- 2014) • Project title: “Iodine in the hydrological cycle in Denmark: implications for human health“ • Objective:to combine both the medical and the geochemical aspect by studying the variations in iodine bioavailability in groundwater and to evaluate the human health effects. Søren Munch Kristiansen Birgitte Hansen Kim Esbensen Vibeke Ernstsen Brian Sørensen

3. Presentation outline • Iodine – essential trace element • Iodine in Denmark • Geochemical aspect • Present work • Data • Method description • Workflow overview • Some results • Conclusions • Future plans and perspectives

4. Iodine – essential trace element Dose-response of essential trace elements • regulates the metabolic processes in cells; plays role in the early development of most organs Safe and adequate intake function toxicity deficiency intake * Expert committee on Human Nutrition, France RNI UL The highest average daily nutrient intake level unlikely to pose risk of adverse health effects Recommended daily nutrient intake

5. Iodine in Denmark Mild iodine deficiency based on median UI = 50-99ug/l (WHO, 2007) Subnational survey data (2 cohorts - Aalborg and Copenhagen; west Denmark – moderate; east – mild) 1998 2000 Voluntary fortification of table salt aiming increase with 50ug/day Mandatory fortification (13mg/kg) of household salt and the salt used for commercial bread production DanThyr Program failed ~25% of iodine intake in the Danish diet is derived from drinking water, coffee, tea and other beverages (Rasmussen et al., 2000) Iodine in drinking water in Denmark varies from 0,7ug/l to 140ug/l (Pedersen et al., 1999, Andersen et al., 2002)

6. Geochemical aspect • Iodine in groundwater – not studies from geochemical point of view • Mapping Regional (and/or temporal) variations • Understanding the involved processes • Finding the source/sources of iodine in the groundwater in Denmark • Available historical data: • From groundwater monitoring programs (mainly GRUMO wells); • Iodine is not part of the waterworks monitoring; • Iodine speciation – important for the geochemical understanding of the Iodine cycle Inorganic iodine Organo-iodine Total iodine

7. Present Work Multivariate data analysis of historical Danish groundwater data • Purpose: to elucidate the iodine source(s) in the sediments, the governing processes of its distribution and variations • Method: exploring correlations between the different data by using PCA and PLS-R • Hypotheses testing: Iodine enrichment: • is originating from marine deposits and infiltrating seawater nearby the present coastline; • is due to desorption of iodine from old Cretaceous marine deposits; Other constituents Geology Distance to coastline Distance to major faults I Is there a correlation? What kind (+/-)? Why?

8. Iodine in Groundwater Status December 2011: 2562 samples Number of Iodine* samples Iodine in groundwater (n=2562)for the period 1933-2011 Iodine concentrations: ug/l ug/l ug/l ug/l ug/l

9. Workflow overview Multivariate analysis Data preparation Extraction of data from the JUPITER ---- DGU number Sample number Screen number Screen depth X, Y lab methods date Geology 26 chemical variables 1 2 28variables: Iodine Li, H2S, CH4, O2, Agg. CO2, NVOC, PO4, SO4, NO3, pH, K, Fe, Mn, HCO3, Ca, Mg, Na, Cl, Fl, B, Ba, Br, Sr conduct. redox, distance to coastline, distance to major faults 5 3 4a 20 variables 505 objects (some missing values) PCA 3 clusters + Background population Interpretation of the MVDA Master set Reduced Master Set, prepared for MVDA Jupiter raw data RMS RMS Data preparation: Variables exclusion Detection limit handling Gross outliers check Objects exclusion 4c 4b PLS PCA Background population 453 objects 3 clusters 52 objects 2562 objects (many missing values)

10. PLS-R model Partial Least Squares Regression Model R²=0,76 (3 PCs, >70% of the variance) 5 4a PCA 3 clusters + Background population Interpretation of the MVDA RMS 4b 4c PLS PCA Background population 453 objects 3 clusters 52 objects

11. Sønderborg Results and Interpretation Gladsaxe Interpretation based on the Loading Weights plot and Score plot (PC1-PC2) Ba Iodine Location HCO3 Ishøj Lejre pH B Br Na faults Sr coast Fe NO3 Jammerbugt Mn K SO4 Frederiksberg Ca Cl Li Mg cond. Water type København

12. Conclusions • It is possible to study the groundwater origin and the processes governing its composition by combining MVDA and traditional hydrogeochemical tools, • Data quality - important issue affecting the outcome of the analysis; • It was not possible to build satisfactory model explaining iodine concentrations based on all samples and the 20 variables • Variables important for explaining the variation in iodine concentration were found (and will be used in next studies) • A new factor, not included in the working hypothesis was found: distance to major faults Geochemical processes releasing Iodine to groundwater: • Based on the PLS model (46 samples) it was not possible to reject the two hypotheses. • desorption from the sediment and • saline water are possible contributors; • breakdown of organic might contribute too.

13. Future plans and perspectives 3 small scale detailed studies • Ishøj, Randers, Skagen • designing a sampling and experimental campaign • Hydrogeochemical aspect: sources and processes on a smaller scale • Improved control over data quality • Relation to existing epidemiological studies National study on Iodine in drinking water • sampling from drinking water wells • reflecting different geological regions, the waterworks size, and the administrative division of Denmark; • speciation, water composition mapping and MVDA • combined study with data from medical registers (spatial correlations with IDD occurrence, specific drug use, or other iodine related health issue)